It is known practice to dye keratin fibers, for instance human keratin fibers such as the hair, with dye compositions comprising oxidation dye precursors, for example ortho- or para-phenylenediamines, ortho- or para-aminophenols, and heterocyclic compounds such as diaminopyrazole derivatives, pyrazolo[1,5-a]pyrimidine derivatives, pyrimidine derivatives, pyridine derivatives, indole derivatives and indoline derivatives, which are generally known as oxidation bases. Oxidation dye precursors, or oxidation bases, are colorless or weakly colored compounds that, when combined with oxidizing products, can give rise to colored compounds and dyes via a process of oxidative condensation. Permanent colorations are thus obtained.
It is also known that the shades obtained with these oxidation bases may be varied by combining them with couplers or coloration modifiers, the latter being chosen, for example, from meta-phenylenediamines, meta-aminophenols, meta-hydroxyphenols and certain heterocyclic compounds.
The variety of molecules used with respect to the oxidation bases and couplers allows a wide range of colors to be obtained.
The use of oxidation bases such as para-phenylenediamine and para-aminophenol derivatives allows a quite broad range of colors to be obtained at basic pH without, however, achieving shades with good chromaticity, while at the same time giving the hair at least one excellent property in terms of strength of color, variety of shades, uniformity of the color and/or fastness with respect to external agents.
The use of these bases at neutral pH may not allow a varied range of shades to be produced, in particular for warm shades such as reds and oranges.